1. Field of the Invention
The present invention relates to a transmission apparatus and a transmission method thereof.
2. Description of the Related Art
Recently, transmission and reception of moving image data via a network have been dramatically increasing. According to a wider bandwidth of the Internet or a widely spread local area network (LAN), the transmission and reception of the moving image data becomes easier than before. However, the transmission and reception of the moving image data still places a heavy load on the network because of a high quality in the moving image and diversification of use of the moving image data.
As a transmission data amount of the moving image data per a unit of time becomes larger, the more number of packets are generated from the moving image data. Consequently, a packet loss due to a discretely-occurred communication error and a communication buffer overflow in a packet relay tends to occur.
As a conventional technique which prevents deterioration of image quality due to the packet loss, a forward error correction method (hereinafter referred to as the “FEC method”) is known. In the FEC method, an FEC creation operation is performed with respect to a group which includes more than one moving image packets to generate FEC packets (i.e., error correction packets) and thereafter, transmits the generated FEC packets to a receiving side together with the moving image packets. A typical FEC creation operation is an exclusive OR operation (i.e., an XOR operation). When the XOR operation is used and one of the moving image packets in a group is lost, other moving image packets which are not lost in the group and the FEC packets are subjected to arithmetic processing, so that the moving image packet which has lost can be restored. The FEC packet can be generated in various manners, by the number of the moving image packets which are formed into a group and a group forming method.
Japanese Patent Application Laid-Open No. 2004-215224 discusses to change an error correction coding parameter based on quality information of a network route between a transmission destination node and a transmission source node.
However, when the moving image data is transmitted to a plurality of transmission destinations, if a setting for a data amount of error correction data differs to each other in every transmission destinations, a large load is produced by generation of the error correction data.
For example, it is assumed that a single FEC packet is transmitted to three moving image packets with respect to one receiving apparatus and a single FEC packet is transmitted to four moving image packets with respect to another receiving apparatus. In this case, if the FEC packet is generated for each of the receiving apparatus, a generation load to generate the FEC packet becomes larger.